Torsion bar construction



Dec. 1, 1964 M. J. STIGLICH TORSION BAR CONSTRUCTION 2 Sheets-Sheet 1 Filed Dec. 1, 1961 I INVENTOR. BY 9444 WxMi A TTOIQIVEVKS Dec. 1, 1964 M. J. STIGLICH 3,159,390

TORSION BAR CONSTRUCTION Filed Dec. 1, 1961 2 Sheets-Sheet 2 TIT-5:3

MfiRT/A/ J. 57/64/04 INVENTOR.

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BY WK M41 4 ATTORWA'YG 3,159,391 TGRSION BAR CGNSTRUCTEON Martin J. Stiglich, Plymouth, Mich, assignor to Ford Motor Company, Dearhorn, Mich a corporation of Delaware Filed Dec. 1, 1961, Ser. No. 156,299 1 Claim. (Cl. 267-57) The present invention relates generally to torsion bar springs and more particularly to a construction for securing the end of a torsion bar.

Particular problems are presented by the use of a torsion bar spring between pivotal-1y oriented members. As an example, special means must be provided to secure the spring ends to the respective members. In addition, means must be provided'to load the torsional portion of the spring.

In accordance with the present invention, it is a principal object to provide a simplified construction for loading and securing thetend of a torsion bar spring.

More particularly, the present invention provides a ton sion bar with a righ-angle bent end portion that is held by a U-bolt or similar device and positioned by the novel geometric configuration of the end portion.

Specifically, the tip of the bent end portion is turned in such a fashion that the spring forces will tend to secure and locate the torsion bar end in posit-ion. Therefore it is one of the specific objects of this invention to provide a unique torsion bar end configuration that is held in proper position by its own spring force.

The objects and advantages of the present invention will be more fully comprehended from the following discussion and the accompanying drawings, in which:

FIGURE 1 is a vehicle suspension system incorporating a torsion bar spring construction in accordance with the present invention;

FIGURE 2 is a side elevational view of the torsion bar end construction of FIGURE 1;

FIGURE 3 is a sectional view taken along section lines 3-3 of FIGURE 2;

FIGURE 4 is a view corresponding to FIGURE 3 showing a modification of the present invention;

FIGURE 5 is a view corresponding to FIGURE 3 disclosing a further modification of the present invention, and; 1

FIGURE 6 is a still further modification of the construction of FIGURE 3. 7

Referring now to the drawings for a detailed description of the present invention, like reference numerals identify like parts throughout the various views.

FIGURE 1 discloses an independent front suspension system employing a torsion bar spring 1% as the resilient means for supporting the sprung suspension components upon the unsprung components.

A vehicle wheel 12 is rotatably mounted upon a wheel spindle 18. The spindle 18 is connected to a chassis frame member 14 by a suspension arm 16. The suspension arm 16 is universally connected to the wheel spindle 18 by means of a ball joint 20 and the inner end of the arm 16 is pivotally connected to a frame mounted pivot bracket 22. p

The torsion bar it) is formed to have a generally \.'-shape with an inner end portion 24 secured to the chassis frame member 14 by means of a U-bolt 26. The outer end of the torsion bar It is secured to the suspension arm 16.

The torsion bar 16 has a pair of torsional spring portions 28 and 30 that are connected by a U-shaped integral portion 32. The angled portions of the torsion bar 1%), such as the major bend 34, that interconnect the straight portions, are enlarged to compensate for the combined bending and torsional stresses that are encountered.

As previously described, the end 24 of spring portion Patented Dec. 1, 1964 28 is secured to the chassis member 14 by the U-bolt 26. The outer end of the torsional portion 39 is provided with a right-angle bent portion 34.

FIGURE 2 discloses the details of the connection of the 'bar end 34 with the suspension arm 16.

The suspension arm 16 is fabricated from sheet metal and has a general-1y angular contour- The torsion bar end 54 is provided with a tip portion 36 that is slightly bent or turned down. The end face of tip 36 bears against a reaction stop member 38 that is welded to the arm 16. The tip 36 rests upon a surface portion 42 of the arm 16.

The inner end of the end portion 34 is secured to the arm 16 by a U-bolt 4a. The U-bolt 40 contains the end 34 against motion in both vertical or longitudinal directions.

Means must be provided to locate the bar end 34- and restrain it against axial movement with respect to the opening through the U-bolt 40. Accordingly, this invention concerns a new method of attaching a torsion bar with a crank end that is bent approximately to the torsional segment of the bar and in which the crank end is positively located and axially contained by means of the geometrical configuration of the bar end.

To insure self-locking and locating of the bar end 34, there must be a force against the reaction member 3% at the tip of the bar 36. This force insures that any impending movement =will be towards the reaction member 38 and not towards the axis of torsional portion 30. In order to achieve this objective, the force tending to push the bar towards the reaction member 38 must exceed the frictional force between the tipof the bar 36 and the adjacent surface 42 of the arm 16.

In FIGURE 2, a certain torsional moment M exists in the torsional portion 30. The moment M produces a reactive force P that is perpendicular to the axis of the end portion 34. Force P has a component force S that is parallel to the axis of the tip 36 and also parallel to the surface 42 of the arm 16 upon which the tip 36 rests. There is also a component N of force P that is normal to the surface 42. A frictional force R exists at the intersection of the tip 36 with the surface 42 that is equal to the coefficient of friction ,u. of the contacting surfaces multiplied times the normal force N.

The tip 36 of the bent end 34 is turned at an angle 5 that is equal to the angle that component N makes with force P. If the force S against the reaction member 38 is to exceed the frictional force R, then it is mathematically determinable that angle [3 must exceed the friction angle (the angle where motion impends). If the angle 3 is to be greater than the friction angle, then the tangent of angle ,8 must be greater than the tangent of the friction angle.

The tangent of the friction angle is equal to ,u., the coefficient of frictionand, therefore, the tangent of angle 3 must be greater than the coefficient of friction. It is a relatively simple matter to determine the coefficient of friction between the surface of the tip 36 and the surface 42 of the arm 16 and this determination will indicate the appropriate angle [3. From the formula that the tangent of angle [3 must exceed the coeflicient of friction, we can determine the extent to which the tip 36 must bend relative to the end portion 34.

The coefficient of friction is extremely variable being dependent upon the materials in contact and upon the condition of the contacting surfaces. A typical coefficient of friction might be approximately 0.3 which, in turn, would mean that the angle [3 should be greater than approximately Thus, according to the theory of the present invention, the tip 36 of the torsion bar may be turned down at an angle greater than 16.5 so that a force S will be exerted against the reaction member 38 resulting from torsional momentM. This force S, in effect,

will tend to prevent the torsion bar end 34 from creeping out of securement by the U-bolt 40. a

In the principal embodiment, the torsion bar tip 34 is of a conventional circular cross section and theoretically has a straight-line contact with the surface 42 of the arm 16. Inorder to obtain more consistentresults, it may be advisable to have an end bar configuration, such as 36a, 3612 or 360 disclosed in the alternate'constructions of FIGURES 4, 5 and 6 respectively. These constructions have a common feature of a bar end that presents a flat face to the sheet metal arm sunface 42; This construction, in addition to providing consistent operation, also reduces the tendency to corrosion.

The foregoing description presents the presently preferred embodiment and alternate constructions of this invention. Other arrangements may occur to those skilled in the art-which will com-e within the scope and spirit rest-ion as the axis of the pivotal connection between said members, said end portion having an axis extending generally normal to the axis of said torsional segment and the axis of the pivotal connection between said memhere, said end portion having a tip portion and said tip portion having an axis said tip portion axis forming a set angle with a radius extending from the axis of said torsional segment and forming an angle with the axis of said end portion, atip receiving surface formed on said one member at an angle complementing the said set' angle, said tip portion having a flat face lying in flush engagement with said tip receiving surface and parallel to said tip portion axis, said set angle of said tip porton axis beng greater thanthe friction angle-between said receiving surface and said flat face, and a reaction member afiixed to said one member and located against the extremity of said tip portion.

References Citedin the file of this patent Australia Sept. 14, 1955 

